The invention relates generally to the field of devices used to form voids in concrete or cement floor slabs, and more particularly to such devices which provide access to the conduits after the slab has been poured. Such devices are set in place at a desired location and connected to conduits to allow various service lines, such as refrigeration, plumbing, and electrical lines, to be pulled through the slab and connected to units above the slab. The device is an access box having a lid which both forms a closed void within the access box and acts as a form to retain some of the concrete, so that the concrete slab can be poured around the device and into the lid at the same time. After the concrete has set, the lid can be pried up to provide access to the void, the lid remaining undamaged so that it can be replaced onto the access box.
Modern construction techniques often use a poured concrete slab for the floor of a structure. In the case of buildings having large open areas, such as a grocery store, it is usually necessary to extend electrical, plumbing, refrigeration or other such service lines to locations in the central areas away from the outer walls. The conduits for these service lines are placed below or within the concrete slab so that the lines are not exposed and in the way, with access ports being situated at the desired locations for the lines to emerge from the floor for connection to the individual machines, refrigerators, etc. In practice, the conduits are laid out on site prior to pouring the concrete floor, running from the edge of the slab or service origin points to numerous access boxes, commonly called pull boxes, situated at the required locations. The floor is then poured and allowed to set, and then the various lines are pulled through the embedded conduits and up through the voids formed by the access boxes to extend out of the floor.
The standard practice for making the access boxes is to build a four sided, bottomless wooden form, the height of the walls being sufficient to extend above the top level of the concrete to be poured. The ends of the conduits, for example, PVC pipes, abut the outside of the sides of the wooden form. After construction of the wooden boxes, the floor is poured with the concrete covering the conduits and surrounding the wooden form. After the concrete hardens, the wooden form must be removed by breaking it out of the concrete slab, since it will deteriorate over time and destroy the integrity of the floor. A concrete bottom is then poured in the void left by removal of the wooden form. The service lines are then pulled through the conduits to extend above the top surface of the floor, and the access void is filled with sand to a height several inches below the slab surface. A top layer of concrete is then poured onto the sand to seal off the access void.
In construction of grocery stores and the like, building and health codes require that the floor be solid and continuous, with no openings to allow ingress of water, air, insects, etc. The floor must have a minimum two inch depth of poured concrete. It is this requirement that dictates the steps of removing the wooden form, pouring a bottom and then pouring a top, so that the resulting floor will be the minimum two inches in thickness above the void and will have a solid, continuous surface. It is often necessary at a later date to gain access to repair the line joints contained within the access void, and with the standard method, the floor must be torn up with jack hammers or the like to remove the top layer and the sand must be taken out. After the problem is corrected, the sand must be replaced and new concrete must then be poured to form a new top layer.
A pre-formed access box, capable of remaining within the slab, has been created to provide a permanent void in the concrete slab The access box is merely set into place, so no form construction is required. The access box has a removable lid which contains the two inch top concrete layer and which is simply pried up and then placed back in position after problems with the line joints have been corrected. The lid has a raised portion to exclude concrete from the area through which the service lines will ultimately extend. The access box enables the top to be poured at the same time as the surrounding floor, thus eliminating the steps of pouring a bottom and then a top to seal the void at a time after the floor itself has been poured, with the corresponding savings in construction time.
It is an object of the invention to provide a pre-formed access box which eliminates a number of steps now required in the construction of access voids in poured concrete slabs, in particular allowing the top layer to be poured at the same time as the surrounding floor.
It is a further object to provide such an access box which has a removable and replaceable lid which contains the top layer of concrete.
It is a further object to provide such an access box where the lid has a raised portion to exclude concrete from the region through which the service lines will be extended.
It is a further object to provide such an access box where the lid seating rim of the main body and the perimeter of the lid itself are flared to allow the lid to be pried from the main body of the access box.
It is a further object to provide such an access box where a portion of the flared lid perimeter and flared lid seating rim are angled greater than the angle of the flaring to provide a pry lip.